1. An anchored chromosome‐scale genome assembly of spinach improves annotation and reveals extensive gene rearrangements in euasterids
- Author
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Shiyu Chen, Allen Van Deynze, Shifeng Cheng, Jason Chin, Kevin Stoffel, Hamid Ashrafi, Linzhou Li, Tyler Garvin, Lindsey J. du Toit, Elizabeth Tseng, Amanda M. Hulse-Kemp, Walter Sanseverino, Massimo Iorizzo, Michael C. Schatz, and Hamed Bostan
- Subjects
0106 biological sciences ,0301 basic medicine ,Sequence assembly ,Plant Science ,QH426-470 ,Amaranthus hypochondriacus ,01 natural sciences ,Genome ,Chenopodium quinoa ,Chromosomes ,SB1-1110 ,03 medical and health sciences ,Spinacia oleracea ,Genetics ,Gene ,Gene Rearrangement ,Peronospora ,Caryophyllales ,biology ,Plant culture ,food and beverages ,Genome project ,biology.organism_classification ,Plant Breeding ,030104 developmental biology ,Spinach ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
Spinach (Spinacia oleracea L.) is a member of the Caryophyllales family, a basal eudicot asterid that consists of sugar beet (Beta vulgaris L. subsp. vulgaris), quinoa (Chenopodium quinoa Willd.), and amaranth (Amaranthus hypochondriacus L.). With the introduction of baby leaf types, spinach has become a staple food in many homes. Production issues focus on yield, nitrogen‐use efficiency and resistance to downy mildew (Peronospora effusa). Although genomes are available for the above species, a chromosome‐level assembly exists only for quinoa, allowing for proper annotation and structural analyses to enhance crop improvement. We independently assembled and annotated genomes of the cultivar Viroflay using short‐read strategy (Illumina) and long‐read strategies (Pacific Biosciences) to develop a chromosome‐level, genetically anchored assembly for spinach. Scaffold N50 for the Illumina assembly was 389 kb, whereas that for Pacific BioSciences was 4.43 Mb, representing 911 Mb (93% of the genome) in 221 scaffolds, 80% of which are anchored and oriented on a sequence‐based genetic map, also described within this work. The two assemblies were 99.5% collinear. Independent annotation of the two assemblies with the same comprehensive transcriptome dataset show that the quality of the assembly directly affects the annotation with significantly more genes predicted (26,862 vs. 34,877) in the long‐read assembly. Analysis of resistance genes confirms a bias in resistant gene motifs more typical of monocots. Evolutionary analysis indicates that Spinacia is a paleohexaploid with a whole‐genome triplication followed by extensive gene rearrangements identified in this work. Diversity analysis of 75 lines indicate that variation in genes is ample for hypothesis‐driven, genomic‐assisted breeding enabled by this work.
- Published
- 2021
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